[Elecraft] Final Update To Keying Mod Change

[Ron D'Eau Claire]

That really interesting John. Thank you for the good effort.=20

Let's see if I understand the levels correctly. A "stock" K2 has a peak
energy in the sidebands at 500 Hz from the carrier that is about 62 db =
below
the carrier. If I'm scribbling correctly here, that means that if the
carrier is at 100 watts output, then the energy at the peak of the =
"click"
is about 0.000064 watts or 64 microwatts.=20

If we use the common scale of 6 db per S-unit, if signal from a "stock" =
K2
at someone's receiver is S9+10 db then the clicks 500 Hz away are just =
at
S-zero. At 1 kHz from the carrier, the signal would have to be about =
S9+20
db for the clicks to be as loud as S-zero. Using the conventional =
definition
of 50 uV for an S-9 signal, an S9+20 db signal is putting a full 1/2 =
VOLT on
the antenna terminals.=20

That's certainly audible if the transmitter is very close to a receiver =
is
capable of handling that sort of RF voltage at the antenna without
overloading. In installations where transmitters and receivers are very
close to each other, the mods can make a significant improvement, =
obviously.


However, in normal on-the air use, I'm not sure the bands are quiet =
enough
for me to hear a noise pulses at S0 or even S1. And they drop in level =
very
quickly as we tune more than 500 Hz from the carrier.=20

Ron AC7AC


-----Original Message-----
I've posted a final update to the 180K resistor value change for the
Elecraft Keying Modification.  This update adds a new way to measure key
clicks from a transmitter.  The new method can distinguish the peak
intensity of a key click rather than the average intensity measurements =
that
are made with a spectrum analyzer.  This better reflects the true effect =
of
a key click on a receiver.

The new method also measures the peak intensity of a key click for both =
the
rising and falling edges of the waveform.  The measurements on the K2 =
show
that in some cases one edge of the keying waveform can generate 10 dB
greater intensity than the other edge.

The latest version of this document can be accessed at:

http://home.pacbell.net/johngreb/improving_elecraft_keyingmod.pdf

-John
 KI6WX